What is the difference between assign and appoint? how about between celebrate and congratulate?

Question

Answer

To assign means to give a job to someone- to tell a person what job they have to do.
To appoint means to give someone a title e.g He was appointed as the new bank manager.
To celebrate is to have a party to mark a certain event - "On Saturday we celebrated my 10th wedding anniversary".
To congratulate means to tell someone that you are happy about some event
"I congratulate you on your wedding".